Wednesday, February 3, 2010

Paleo Diet Q & A - 3 February 2010 - Milk During Pregnancy

Dear Readers,

Today's edition of Paleo Diet Q & A focuses on consumption of milk during pregnancy.

Q: Hi Dr. Cordain,

My sister is a few weeks pregnant and has been following the Paleo Diet for a couple months now. Her doctor just told her to consume lots of milk during her pregnancy. My assumption is that they want to make sure she's getting plenty of vitamin D and calcium. I have her on a 2000 IU/day vitamin D supplement as well as a calcium/vitamin D supplement. What are your thoughts/suggestions?

Drew

A: Dear Drew,

There is good evidence that up until 9,000 years ago in the Middle East1 and 7,000 years ago in Northern Europe2, no human being on the planet consumed non-human milk or dairy products.

So, on an evolutionary time scale non-human milk is a relative newcomer to the human diet.

By using the evolutionary template, and knowing that milk is species-specific, we would expect this new habit to have unintended consequences, which go much beyond lactose intolerance, which is, actually very common, since only a minor percentage of the world’s population continues to produce lactase into adulthood3.

Indeed there are several lines of evidence raising concerns with milk and dairy intake, such as:

1) Milk and fermented milk (yoghurt, for instance), despite having a low Glycemic Index and Load, elicit a very high insulin response and this has been shown repeatedly in intervention studies4-9.

As you may be aware, constantly increasing insulinemia may down-regulate the insulin receptor and hence lead to insulin resistance10-12. Thisin turn is the primary metabolic defect underlying The Metabolic Syndrome13, and may be a driving force in Obesity14, 15. It should also be mentioned that a chronic state of Hyperinsulinemia may initiate a hormonal cascade that ultimately results in Cancer, Acne and Juvenile Myopia, among other diseases13 (as thoroughly documented in Dr.Cordain’s scientific paper Hyperinsulinemic diseases of civilization: more than just syndrome X which you can download here.

Indeed, a high bovine milk diet has been shown to cause insulin resistance in boys9. Moreover, dairy intake is strongly associated with a higher incidence of Acne16-18 and moderately associated with Prostate Cancer19-23.

There is molecular mimicry between Bovine Serum Albumin and Human Collagen Type 1, which has implications for Rheumatoid Arthritis37. Indeed, case studies have shown that elimination of milk and dairy products from the diets of patients with RA improved symptoms, and the disease was markedly exacerbated on re-challenge37.

Bovine Milk is also implicated (or appears to have adverse effects) in other auto-immune diseases, such as Crohn's disease38, Sjögren's syndrome39, IgA nephropathy40-42, Behçet's disease43, and even Celiac Disease40.

3) Hormones in Milk:

In addition to proteins, fats, lactose, vitamins and minerals, Milk contains various growth-stimulating steroid and peptide hormone and also catalysts, transporters and stabilizers that ensure their maximum bioactivity45.

Here’s a short list of some hormones present in cow’s milk that could be problematic for humans:

Insulin

IGF-1

Betacellulin (BTC)

Estrogens (particularly Estrone Sulfate)

Precursors of Dihydrotestosterone (DHT)

Insulin

Cow’s milk, as well as human milk (and presumably milk from all mammals) contains insulin46-49, and we know that bovine insulin - BI (which differs from human insulin by three amino acids50) survives pasteurization, because immunity to this hormone is common in children who consume cow’s milk or who have been exposed to infant formulas containing cow’s milk51-54.

This not only confirms that BI is present in commercial pasteurized milk, but also in infant formulas and perhaps other dairy products (although direct evidence is lacking). Moreover, these studies provide evidence that BI survives the human digestive processes and crosses the gut barrier intact, although this could be related to the fact that infants have higher intestinal permeability than older children and adults50. Nevertheless, various factors may cause the so called "leaky gut" in virtually everyone, so we shouldn’t dismiss bovine insulin altogether.

IGF-1

Cow’s milk contains active IGF-155, but this has been largely dismissed as irrelevant, since pasteurization (time and temperature are crucial factors) and fermentation appears to reduce its content56, 57. Yet cow’s milk consumption, compared to various foods, is associated with higher plasma IGF-1 concentrations in humans (both children58-61 and adults62-66, which could be due to calcium in milk (which has been shown to increase IGF-1 in boys and girls67), the effect of milk upon insulinemia (the high elevation of plasma insulin caused by milk drinking4-9 could lead to a higher plasma IGF-113) or indeed residual IGF-1 in casein68 (the major protein in milk).

Betacellulin

Betacellulin (BTC) belongs to the Epidermal Growth Factor family of hormones69, and it is found not only in cow’s milk70 and whey70, but also in cheese70, so it survives pasteurization and processing. Although no direct evidence exists yet, bovine milk contains peptidase inhibitors which prevent human gut enzymes from degrading EGF5 (and most likely BTC) and a low ph, such as may be found in the gut, does not impair or prevent BTC from binding its receptor71. Finally, there is a luminally expressed EGF receptor in the gut, through which BTC may enter circulation69.

Steroid Hormones

The major sources of animal-derived estrogens in the human diet are believed to be milk and dairy products, which presumably account for 70–80% of the total estrogens consumed72-73. Furthermore, it has been pointed out that most milk for human consumption is obtained from cows in the latter half of pregnancy, when estrogen metabolite levels are greatly elevated72-74. Confirming this, US researchers have measured estrogen metabolites in various milks and found that buttermilk contains the highest total amount of estrogen metabolites, followed by skim milk, 2% milk and whole milk72. So, estrogen metabolites appear to survive pasteurization, and Estrone sulphate, which comprises 45% of the conjugated estrogens in Premarin and Prempro, the most frequently prescribed hormone replacement therapy for menopausal women73 has high oral bioactivity73 and is the most prevalent form of estrogen in cow’s milk72, 73.

There are also other steroid hormones in commercial pasteurized cow’s milk, such as progesterone, 5α-androstanedione and 5α-pregnanedione that are dihydrotestosterone (DHT) precursors75.

As expected from the evidence presented, dairy intake is strongly associated with a higher incidence of Acne16-18, moderately associated with Prostate Cancer19-23, and mildly associated with ovarian cancer76, 77.

Dairy consumption was also associated with an increased incidence of testicular78-79, kidney80 and head and neck cancer81, but very few studies looking at this have been conducted to draw more significant conclusions.

Although epidemiological evidence can’t show cause and effect and clearly many more studies need to be conducted, the current evidence strongly suggests that cow’s milk may be implicated in a variety of autoimmune diseases, certain cancers, as well as Acne.

4) Milk has a very high calcium/magnesium ratio and may contribute to some micronutrient imbalances.

Finally, there is evidence of higher fracture incidence rates in countries with higher milk and calcium intake82, some long term prospective studies have failed to show a benefit from drinking milk or taking calcium supplements83-85, and a recent meta-analysis, which analyzed 7 prospective cohort studies (170 991 women), 5 prospective cohort studies (68 606 men), 5 clinical trials, (5666 women, and 1074 men), and 4 clinical trials with separate results for hip fracture (6504 subjects), concluded that calcium intake doesn’t decrease the risk for fractures86. And calcium intake is only part of the story – we need to consider the GI absorption and the renal excretion, and in these regards, vegetables from the brassica family have a clear advantage over milk.

I know this may sound overly alarming and exaggerated, but given what I know about milk, I have a hard time recommending it, even though it has some positive effects, such as being a cheap source of high quality protein and various micronutrients.

For those who are fortunate and have access to good (real) food and supplements (such as Vitamin D, which, by the way, may be needed in much higher doses than the ones provided by 3 or 4 servings of dairy a day) and adopt a diet more in line with the Paleo Diet, I believe milk is not necessary.

3 comments:

You must make a definition between raw and pasteurized milk in your answer Dr. Loren. Many primitive tribes survive on meat, blood and raw milk and Weston A. Price has made a study of people who thrived on raw milk, cheese and butter (I live two hours away from the original Swiss valley Price visited to study). Raw milk is high in vitamin A (primal diets found to contain ten times more vit. A than modern diets) and crucially it is not isolated like modern supplements are, but consumed in conjunction with other compounds such as Activator X, discovered by Price in Raw Butter from cows eating rapidly growing grass.

There is no need to ingest high-doses of synthetic chemicals as you advise, the results of which we do not really understand. Price went to great lengths to show how primal cultures would go out of their way - literally days and days of walking out of their way - to provide special food for pregnant women high in vitamin A such as seafood (roe) and honey (hence the name honeymoon - newly weds were fed honey for one month to ensure they were fit and able to conceive).

Native Americans made sure pregnant and feeding women had the liver and organ meat above the other members of the tribe.

Synthetic vitamin A may harm a growing baby, but not vit. A from raw milk or liver - this is something history shows us again and again.

Yes, there are people who are lactose intolerant, and the majority of people alive today are probably allergic to pasteurized milk (a dead food which the body's defenses valiantly attack - giving rise to many of the symptoms and diseases you cite above) but if the questioner's sister can get hold of raw milk or failing that, liver or raw honey then she will be giving her unborn child a triple whammy of primal nourishment modern pharmaceuticals cannot even grasp hold of.

(sorry I do not have more references to refer to as in this post, but any close study of Price's (www.westonaprice.org) work will provide all the scientific evidence needed about raw milk).

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